Simulated In-Situ Immobilization of Heavy Metals in Selected Soils of Karnataka

Chemical remediation of heavy metal infested soils is gaining importance owing to the multifaceted approach in creating ideal physical, chemical and biological conditions in the rhizosphere ensuing higher productivity. Three representative soils belonging to Alfisols, Vertisols and Ultisols spiked with 100 ppm of each Pb, Ni and Cd was treated with ameliorants like agricultural lime, potassium di-hydrogen orthophosphate (KH2PO4) and compost. Sequential extraction procedure was adopted to determine the phyto-available fraction constituting water soluble, exchangeable and carbonate bound metal with the perspective of remediation. Potassium di-hydrogen orthophosphate was the most effective chemical in attenuating Pb as indicated by the lowest phyto-available fraction in soils followed by agricultural lime and compost. For Cd, agricultural lime was superior to other amendments in all the soils. However, among the different ameliorants compost was most efficient in immobilizing Ni in all the soils.